The invention relates to a device for HF-coagulation of biological tissues by means of flexible endoscopy, a mobile applicator for supplying ionizable gas and containing a current supply connection line to an active mobile electrode able to be placed in a working channel of the endoscope catheter at the distal end.
A device for coagulating of biological tissues, particularly in the gastrointestinal tract, is known from Patent DE 41 39 029 C2. A connecting line for connection to an HF voltage source is located in a working channel of an endoscope. In addition, an ionizable gas is supplied through the working channel, which emerges at the distal end of the working channel. Provided in the flow path of the gas in front of the outlet from the outlet opening is an electrode, which serves to ionize the gas and to supply the coagulation current. The electrode is fixed in position in such a way that it cannot come into contact with the tissue to be coagulated. Undesirable burning or other irreversible damage to the tissue is, therefore, to a large degree eliminated in the solution indicated above.
There is known from U.S. Pat. No. 5,207,675 a coagulation device which likewise can be used in conjunction with an endoscope. Within a flexible tube, which is accommodated by the catheter of the endoscope, there is located a current supply, which is in turn connected to an electrode provided at the distal end. The electrode merges into an electrode point, in order to permit a controlled arc discharge.
Patent WO 93/01758 discloses a pipeline which serves to supply an ionizable gas such as argon, and in the distal end of which an electrode is movably arranged in such a way that it can be advanced from a position within the pipeline to a position partly or wholly outside the distal end of the pipeline.
Both in exogenic methods for blood stypsis by means of hot probes and also in endogenic methods by means of HF-current, the source of bleeding must be brought into thermal or electrically conductive contact with the probe or the coagulation electrode. Problems, however, exist in that the coagulate can adhere securely to the probe or the coagulation electrode, so that when the electrode is removed the source of bleeding is again torn open. Finally, the known methods for stypsis of large area diffuse sites of bleeding are extremely time-consuming. In the known argon-plasma coagulation, there is no direct contact between the active electrode and the tissue surface to be treated. Rather the voltage present at the electrode ignites a plasma discharge of the supplied ionizable gas, namely argon. The advantage of argon-plasma coagulation resides on the fact that the depth and the effective thickness of the coagulation is limited by a developing, thin, 2nd electrically insulating layer on the tissue layer treated. Not least for this reason, argon-plasma coagulation plays an important part in applications in the gastrointestinal tract.
It is, however, disadvantageous that HF surgical instruments, which have previously become known particularly for flexible endoscopy, are not simply suited for contact coagulation or for non-contact coagulation and/or for cutting. Due to the different currents and voltages which are necessary for the respective treatment method, there is a risk that when the active electrode is brought into contact with the tissue, during deliberate non-contact mode, irreversible tissue alterations will occur.
Hence, there is a need for an apparatus to provide HF coagulation of biological tissues without altering the tissues or tearing the tissues upon removing the apparatus. It is further desired to provide a HF coagulation apparatus that can be used in conjunction with an endoscope and catheter and permits both contact and non-contact coagulation.